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. 2010 Sep 22;299(6):R1582–R1591. doi: 10.1152/ajpregu.00402.2010

Fig. 3.

Fig. 3.

Relative proportions of IIX/IIB isoforms in TA and BR muscles (A and B), relative proportions of IIX, IIX/IIB, and IIB fiber types. A: brachioradialis muscle had 47.8% of its fibers as IIX/IIB hybrids (n = 339 fibers). B: TA muscle had 25.5% IIX/IIB hybrids (n = 392 fibers). The remaining fibers in both muscles were either pure IIB or IIX fibers. C and D: relative proportions of IIX and IIB isoforms within single IIX/IIB hybrid fibers. IIX/IIB hybrid fibers within the BR muscle exhibit a range of MHC isoform proportions that are fairly normally distributed ∼50:50 mix of IIX/IIB (n = 57 fibers) (C). Hybrids within the TA muscle display a similar range of IIX/IIB isoform proportions (n = 71 fibers) (D). Shading corresponds to the relative levels of IIB (white) or IIX (black) MHC present in hybrid fibers.